Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Some aircraft may have more than fifty percent of their primary structure made from composite materials. Composite materials are used in aircraft to decrease the weight of the aircraft. This decreased weight improves performance features, such as payload capacities and fuel efficiencies. Further, composite materials provide longer service life for various components in an aircraft.
Composite materials are tough, light-weight materials, created by combining two or more dissimilar components. For example, a composite may include fibers and resins. The fibers and resins are combined and cured to form a composite material.
By using composite materials, portions of an aircraft may be created in larger pieces or sections. This is called integrated structure. For example, a fuselage in an aircraft may be created in cylindrical sections that may be put together to form the fuselage of the aircraft. Other examples include, for example, without limitation, wing skins, span-wise stiffeners, spars and chordwise ribs joined to form a wing, stabilizer sections joined to form a stabilizer, a stiffener, a fairing, a control surface, a skin, a skin section, a door, a strut, and a tubular structure.
In manufacturing composite components, the materials typically are formed using a mold. These molds also are referred to as tools. A tool has sufficient rigidity to maintain the desired shape for the composite component when the composite materials are placed onto the tools. A tool may be metallic or non-metallic in composition to provide rigidity for supporting the composite materials.
Currently, many composites in a manufactured aircraft require an autoclave to cure the composite components. Resins in pre-impregnated plies typically need an elevated temperature to achieve a chemical reaction that allows these resins to flow and cure, and an elevated pressure to achieve ply consolidation and expel gases contained within the pre-impregnated plies, known as porosity. With large components, a large autoclave is needed to encompass the component and the tool for processing.
Conventional composite manufacturing processes often encounter undesirable inconsistency, which may in turn result in reduced yield, increased scrap and rework, or performance/weight penalties resulting from reduced design allowables (structural knockdowns). Examples of common undesirable inconsistency include those associated with porosity, manufacturing tolerances due to spring-back and warping and adhesion and wrinkling of the first ply down, or subsequent plies in the part stack under consolidation vacuum. It may therefore be desirable to have an apparatus and method that addresses these challenges, improves upon existing practices and having the potential to work within existing process specifications.